Israel's army says a total of 21 soldiers were killed in an attack in central Gaza, making it the largest single loss of life for the military since the war began.

"The reservists were preparing explosives to demolish two buildings in central Gaza on Monday when a militant fired a rocket-propelled grenade at a tank nearby, Rear Adm. Daniel Hagari, the chief military spokesperson, said. The blast triggered the explosives, causing both two-story buildings to collapse on the soldiers inside."